Embodiments of the present invention relate to sound output devices that are capable of outputting sound by using an electric tool battery as a power source.
At construction sites where interior outfitting of houses or the like is performed, nowadays more and more battery type sound output devices such as radio sets with speakers are used for enjoying music, where said devices typically employ electric tool batteries as the power source (See e.g., publication JP2013-12984A). The electric tool batteries are rechargeable batteries not only used in the sound output devices but also as the power source for the electric tools utilized for the interior outfitting work. Some of these battery type sound output devices may also be compatible and capable of use with portable electric apparatuses such as smart phones, tablets, portable music players, and portable game machines.
The speakers described above are used at interior outfitting construction sites, where dust is likely to fume up. Thus, in order to mitigate the harmful impact of the dust, the speakers adopt a hermetic case structure, to enhance the dustproof/waterproof effect. Through the use of the hermetic case structure, however, while it is possible to enhance the dustproof/waterproof effect, one of the drawbacks is that low-sound frequencies of the output sound frequencies may be excluded. Consequently, as a result, the listener often complains of a rather poor tone quality.
There is thus a need for a battery type sound output device which is capable of both a high dustproof/waterproof effect and outputting a sound of high tone quality, without excluding low-sound frequencies.